JPS60179466A - Highly heat-resistant corrosion-resistant pigment composition - Google Patents

Abstract

PURPOSE:To provide a corrosion-resistant pigment having corrosion-resistant performance equal to that of zinc powder and high heat resistance, by incorporating a higher aliph. amine in an alloy comprising zinc, silicon and aluminum. CONSTITUTION:A corrosion-resistant pigment compsn. is obtd. by incorporating 0.05-3.0pts.wt. higher aliph. amine in 100pts.wt. powder of a flaky aluminum alloy consisting of 20-50wt% zinc, 10-25wt% silicon and the balance of aluminum and inevitable impurities. The pigment compsn. can be prepd. by forming molten aluminum alloy and atomizing the molten alloy to form a spherical or tear drop-form atomized powder or by shredding an aluminum alloy foil having the above alloy composition to form a shredded foil. The powder or the foil is then mechanically crushed by using said higher aliph. amine as a crushing aid to obtain the desired pigment compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flaky aluminum alloy powder anticorrosion pigment composition that has a high degree of heat resistance and a high degree of sacrificial corrosion protection effect on iron. In particular, the present invention relates to an anticorrosive pigment composition suitable for use in hydrochloric acid-curing alkyl silicate coatings.

Tanks and the like are built using a one-but-one construction method. In this construction method, the steel plates are shot blasted to remove mill scale and red rust, and then a temporary anti-rust coating called shop primer is applied.

After this, the block is assembled through processes such as enlarging the drawing to its original size using electronic markings, baking it onto a steel plate, fusing, bending, and welding. After this, the block is further block 1
The purpose of the shop primer is to prevent the steel plate from rusting for 1 to 3 months until this block painting is applied. As for the performance of the shop primer, it goes without saying that it has excellent anti-corrosion properties, but it is also important that there is little thermal deterioration of the coating film performance due to fusing, welding, strain relief, etc. As shop primers, Hatsu A-touch primer, zinc clinch primer, and non-zinc primer are commercially available. Demand for inorganic zinc-rich primers with excellent properties such as lI<, 3/i and heat resistance has rapidly increased, and they have become the mainstream of shop primers. ing.

Inorganic zinc-rich primer is a paint containing alkali silicate or alkyl silicate as a binder and zinc powder at a high concentration.It has high corrosion resistance due to the anodizing effect of zinc powder, and has excellent properties due to the heat resistance of the binder. This shows that. However, even the current inorganic zinc-rich primers do not solve the problem of thermal deterioration of paint film performance caused by fusing, welding, strain relief, etc., resulting in burnout of the paint film at the welding area, thermal deterioration of the strain relief area, and peeling of the paint film. The problem still exists and there is significant rusting in these parts.

Zinc prevents iron from rusting by acting as a highly sacrificial anode on iron, but since it has a low melting point and is easily volatile, it easily turns into steam when exposed to high heat during processes such as cutting, welding, and strain relief. It becomes vaporized. In addition, the coating film often cracks or peels off due to rapid heating. Areas where the zinc powder has disappeared no longer have any anticorrosive effect, and the zinc fume generated is toxic, so special care must be taken during work.

The following techniques have been disclosed as methods for solving these problems, but each has its own merits, and it has been desired to develop an anticorrosion pigment that has a high degree of anticorrosion and heat resistance.

Japanese Patent Publication No. 47-27765 discloses a technique using an aluminum alloy powder containing 5% or less of Zn, but this aluminum alloy powder has poor sacrificial anode action and has not been put to practical use.

Japanese Patent Publication No. 47-51090 discloses a technique using Zn alloy powder containing 1 to 50% A1.

Although this alloy powder has a sufficient sacrificial anode effect, it has not been put to practical use because its heat resistance has not been sufficiently improved.

In addition, in Japanese Patent Publication No. 55-14873, flaky zinc powder and flaky heat-resistant application material (flake-like aluminum pigment,
A technique using flake graphite pigment, flake cloud BJ face #1) is disclosed. This technology LJ has been partially put into practical use, but when the content of flaky heat-resistant pigment increases, the corrosion resistance decreases and the physical properties of the coating film decrease. It has the contradictory property of insufficient heat resistance, and has not yet achieved satisfactory performance as a shop primer, which requires a high degree of heat resistance.

When 50% or more of zinc is added to aluminum, a sacrificial anode effect on iron is observed, but this may suppress the formation of a passive film on aluminum or cause the oxide film to become conductive. Presumed. However, when an aluminum alloy containing more than 1 iF+n of zinc is heated to a high temperature, the zinc volatilizes rapidly and the corrosion resistance of the heated portion is significantly reduced. Also fusing and welding.

In processes such as strain relief, the coating film undergoes rapid heating, resulting in many cases of peeling and peeling of the coating film.

As a result of intensive research to solve these problems of conventional anticorrosion pigments, the present inventors have achieved a high degree of corrosion resistance and heat resistance by adding an appropriate amount of silicon to a lead-aluminum alloy. It has been discovered that an aluminum alloy powder pigment having the following properties can be obtained.

The present invention provides flaky aluminum alloy powder 1 containing 20 to 50% by weight of zinc and 10 to 25% by weight of silicon, with the balance being aluminum and unavoidable impurities.
0.05 to 3.0 parts by weight per 00 parts by weight of luxury clothing 1]
This is an anticorrosive pigment composition containing a Group 7j amine, and provides an anticorrosive pigment that has anticorrosion properties equivalent to that of zinc powder and exhibits high heat resistance.

The anticorrosive pigment composition of the present invention can be obtained by preparing a molten aluminum alloy having the above composition, and producing spherical or teardrop-shaped so-called atomized powder from the molten alloy by an ahemization method, or by producing an aluminum alloy foil having the alloy composition. It is easily produced by producing shredded so-called shredded foil, followed by mechanical grinding using a higher aliphatic amine as a grinding aid17. Mechanical pulverization can be carried out by dry pulverization with a ball mill in an inert gas atmosphere, or with a ball mill, vibration mill,
Wet grinding methods such as in an attriter mill may be used.

Higher aliphatic amines that can be used in the present invention include caprylamine, laurylamine, myristylamine, stearylamine, oleylamine, dilaurylamine, distearylamine, dimethyl A-cutylamine, dimethyldecylamine, dimethyllaurylamine, and dimethylmyristylamine. Examples of the laminate include dimethylpalmitylamine, dimethylstearylamine, tricaprylamine, methyldistearylamine, and methyldilaurylamine, which may be used alone or in a mixture. The content of the higher aliphatic amine is flaky aluminum alloy powder 1
It is 0.05 to 3.0 parts by weight per 00 parts by weight.

As the binder for the tunorminium alloy pigment composition Machida of the present invention, various conventionally commonly used binders such as epoxy, alkyd, and silicone resin can be used. An alkali silicate binder with excellent heat resistance,
Alkyl silicate-based binders and alkyl titanate-based binders are preferred.

1 ift c1 degree of paint in paint is 20 to 5 in pigment volume concentrate.
0%, preferably 20-40%.

For painting, air spray, airless spray, brush painting, etc. can be used, depending on the purpose.The principle of the present invention will be described next.

In order for the anti-corrosion pigment to have a 1N anode effect, it is essential that there is electrical contact between the pigment and the steel plate and that the pigment has a sufficiently medium electrode potential with respect to iron.

Prisoner! II! The electrode potential of lead and mild steel is 0.1NI:I
Te against the water electrode! Il! Lead ta -1,10V, mild steel t; L -0,58V te. On the other hand, aluminum is -0.85V. Aluminum can be expected to have a sufficient sacrificial anode effect on iron from the electrode potential alone, but in reality, aluminum has no sacrificial anode effect on iron at all. The reason for this is that the new surface of aluminum has 1
This is because a highly conductive passive film is formed.

The electrode potential of silicon is -0, with respect to the 0.1Ntj ice electrode.
26V, which is a metal that is more negative than iron, and cannot be expected to have any sacrificial anode effect by itself, but when added to zinc-aluminum alloy, it has been found that an improvement in the sacrificial anode effect is generally observed. This finding led to the present invention. Although the mechanism behind this improvement in the sacrificial anode effect is not clear, it is presumed that it is due to the high conductivity of the oxide film or to the suppression of the formation of an aluminum passive film.

Silicon content: 10 to 25 weight%, preferably 12 to 20 weight%
By adding sacrificial lead in the aluminum alloy, a high sacrificial anode effect can be obtained when the sacrificial lead content is 20 to 50% by weight, preferably 30 to 40% by weight, and the aluminum alloy has a high sacrificial anode effect even when heated to high temperatures. It maintained corrosion resistance.

Furthermore, alkali silicate and alkyl silicate containing 2 to 1 of the flaky alkaline earth metal pigment composition of the present invention,
The paint film is conventional! lI! Compared to paint coatings using lead powder or zinc-aluminum alloy powder, peeling resistance due to rapid heating was remarkable (it became cloudy).The reason for this is that the flaky aluminum of the present invention Since the alloy powder pigment composition contains silicon, it has a strong bond with the binder and forms a strong paint film.
1 [defined.

In addition, the product of the present invention is one in which aliphatic amines used as grinding aids are strongly adsorbed on the surface of flaky aluminum alloy powder. It became clear that this had a significant improvement effect on the strength of the coating film.

Although the reason for this is not clear, the adsorbed aliphatic amine in the present pigment composition forms a salt with some hydrochloric acid and is separated and removed from the surface of the flaky alloy powder. As a result of the disappearance of the hydrophobic coating by the absorbed aliphatic amine and the transformation into surface-active flake-like alloy powder, the individual flake-like alloy powders strongly interact with the alkyl silicate binder, which is determined by Jlt.

When the content of aliphatic amine (6) is less than 0.05 parts by weight per 100 parts by weight of flaky aluminum alloy powder,
Although the coating film strength is strong, the cohesive force between the flakes is too strong and the dispersibility is poor due to the extremely hard muddy texture.On the other hand, when the amount exceeds 3.0 parts by weight, the dispersibility is good but the coating film strength tends to decrease. It was done.

In addition, in the case where a higher fatty acid is used as a grinding aid, the strength of the coating film is extremely low, as is clear from the comparative examples described later, and it is impractical.

It is advantageous to add a very small amount of higher fatty acids or their alcohols to the pigment composition of the present invention because it can slightly extend the bottle life of the paint.

Furthermore, since the pigment composition of the present invention is flaky,
Naturally, since the sedimentation rate of M in the paint is slow and the hiding power is large, the paint film has a good ability to prevent air oxidation and a good ability to prevent corrosive components from permeating in the outside air. . Therefore, the pigment composition of the present invention can be used not only for shop primers but also for heat-resistant paints for heating furnaces, flues, etc.

An example of this defense is shown below: 1゜Example steel hole 50! +, mineral spirit 0.8
j! , a grinding aid, and the atomized powder in the amount shown by the following formula were placed in a 500X alloy specific gravity ball mill and ground through a 250 mesh sieve (visual 63μ) until the residue was about 2%. The grinding time required to achieve a 250 mesh sieve residue of about 2% varied depending on the alloy composition and the amount of grinding aid used. In addition, in Comparative Example 1, zinc powder 3
In Comparative Example 9, V) Alloy 71-mize f&) (-44μ) containing no crushing aid was used.

After crushing, 19.24! Wash out the crushed alloy powder from the ball mill with mineral spirits 1~, pass it through a 250-mesh screen, and suck the metal powder slurry that has passed through the 250-mesh screen to remove the metal content, which contains about 80 m.
% flaky aluminum alloy pigment composition was obtained. Incidentally, during the pulverization, the type of the pulverizing aid and the amount of addition ti were variously changed. The content of the grinding aid was determined based on the amount extracted with ether-acetone from the flaky aluminum-containing pigment composition obtained by suction filtration.

A paint varnish was prepared with the following composition.

Ethyl silicate 4050 Ichitan% (manufactured by Tama Chemical Industry Co., Ltd.) 5% hydrochloric acid water 1 Isopropyl alcohol 43.2 Pure water 5.8 Total 100 The pigment volume concentration of the paint is 40% in all cases except for the dispersibility test.
I adjusted it so that While the specific gravity of zinc is 7.13, the specific gravity of the flaky aluminum powder used in the present invention is about 3.5 to 5.0, so the specific gravity was calculated from the alloy composition and the pigment The weight addition m was adjusted so that the volume concentration was constant.

Test pieces A sandblasted steel plate with a diameter of 70 x 150 x 2.3 mm was coated with a sample paint using a brush.

The coating film was allowed to dry at room temperature, and after 4 days of application, it was subjected to the following test.

The pencil hardness test of the paint film was conducted using the brush-coated plate.
In accordance with the pencil scratch test method of S-5400, the paint film was scratched with pencil marks of different hardness, and the hardness of the paint film was determined from the hardness of the marks when the paint film broke. It shows that 6B is the softest and <9H is the hardest.

The salt spray test was carried out according to the method described in JIS-K5400, and after 300 hours, the state of rust in the scratched area and the state of rust on the entire surface of the paint film were visually observed. Those with slight rust on the scratched area were rated as 09, and those with significant rust on the entire surface were rated as x. This salt spray test was conducted before and after the heat resistance test described below.

The heat resistance test was carried out from room temperature to 700°C in 4 hours. After holding at 700°C for 30 minutes, it was slowly cooled to room 6.

This test piece was subjected to a salt spray test after the heat resistance test.

The sedimentation rate was evaluated by putting ethyl silicate paint 10 (7) with a pigment volume concentration of 40% into a measuring cylinder, shaking it well, allowing it to stand, and measuring the sedimentation volume after 10 minutes.

The dispersibility was measured by placing the aluminum alloy powder pigment composition weighed to give a pigment volume concentration of 20% and the above-mentioned paint varnish in a can, and conducting a pigment dispersion test (for 1 hour). Using a shibu gauge, those dispersed in particles with a size of 60 μm or more were judged as 0°, those with remaining particles of 10 μm or more were judged as ×, and those in between were judged as Δ.

As is clear from the results shown in Table 1, zinc
It can be seen that when the aluminum-cum alloy containing 10% or more of silicon is added, the anticorrosion properties are significantly improved. Furthermore, it can be seen that coating films using these alloy powders have a high degree of corrosion resistance even when heated to 700°C.

As the silicon content increases to 25% by weight, the corrosion resistance decreases.The reason for this is that the electrode potential is higher than that of iron, and as silicon increases, It is assumed that the sacrificial anode effect is lost as the potential approaches the iron electrode potential.

The higher the zinc content, the better the culm corrosion resistance, but as the zinc content exceeds 50% by weight, the heat resistance decreases, making it impossible to satisfy the required performance. The reason for this is presumed to be that as the zinc content increases, the volatilization of zinc during heating becomes more intense, causing a significant volume reduction of the pigment particles.

Sancho Itono: Ariguchi stop! 2) Director-General of the Toku-Nia 1 Agency Name Kazuto Sugi Indication of Hall 1, Ko-i'1 0 (1wa 59 Toku-no-1' [Gan No. 33
97 March 2, Title of invention: Highly heat-resistant anticorrosive pigment composition 3,
Person making the amendment 1! 1 - What relationship does Patent ♂ 1 Applicant Name Toyo Aluminum Co., Ltd. 4 Agent 1-14 Shinjuku 1-chome, Kaijuku-ku, Tokyo Lll [1, 1 Pill 5, Supplementary] Date of 1F Order Voluntary Issue 8, Contents of Amendment (1) Particulars m, page 13, line 5 [Paint! ♂membrane]
The text has been corrected to read [painted i11 membrane or steel plate].

(2) Specification 11; In the middle, 16th chapter, 4th tjl, the word "most hard" is amended to read "most hard."

(3) Ming#+11? ii, page 16, line 13, beginning with "up to 700°C", "up to r -100'C"
and complement i' [! Jru.

(4) In Specification 1 (), 17th Tl, line 7 and lines 7-8 of the same page, [Shibu gauge 1], 1 Tsubu gauge j
3゜(5) In the specification, page 17, line 13, 110% r1;'' is corrected to ``10% by weight.''

Claims (1)

[Claims] (1) Flaky aluminum alloy powder 100ffiJ1 consisting of zinc, silicon, aluminum and other unavoidable impurities, with a zinc a content of 20 to 4% in 50% and a silicon content ω of 10 to 25% by weight 0.0 per part.
A highly heat-resistant anticorrosion pigment composition containing 0.5 to 3.0 parts of higher aliphatic amine.